I don’t know if I’m qualified to answer this at all, but I’ll do my best! Before I start, this is how I draw Sans, how you choose to draw him entirely depends on what feels more comfortable to you and your style. (I tried drawing Sans a bunch of different ways until I found a style that suits me.)
FIRST!! Start off with a ‘t’ shape (we all know the drill but its super important to help figure out where his face goes and how to shape his face)
After all that noise, you can shape his face around the ‘t’. It helps a lot when you’re figuring out his jaw situation.
Again! Use the lines to figure out where to add his face! (*gasp*! he’s already cute af)
Sans is all curves. (one of the reasons drawing him is so therapeutic for me)
Make him round! Add some poofy clothes! Tell him he’s pretty!
Basically my tips are don’t underestimate the ‘t’ and Sans is at his most powerful the rounder he is.